06 – new DC/DC buck design

A project log for Universal LiPo/Li-ion UVLO (undervoltage lockout)

Feature-packed over-discharge protection. Set the cell-count (2S to 7S), minimum cell voltage and dip-time below threshold. Fully hackable!

JanJan 06/25/2019 at 20:410 Comments

After all but the last regulator blew, I wanted to test a DC/DC power supply next. So I quickly made a little board around the Rohm BD9G102G-LB DC/DC buck regulator which is quite close to the reference design from the datasheet.

Aisler online rendering
KiCad rendering - parts included

The boards are 25x20mm in size. I use a bigger inductor than is probably needed for 20mA max output, but I wanted to try a few different ones and look at the output waveform on my scope. Rally can't tell how the ripple will affect the ADC readings of the chip. We will see how that works out. Found a nice paper on reducing ripple by TI...

I'd love to use a small 1206 chip inductor to keep everything nice and small! Resistors and caps will be 0603 instead of 0805 too for the final board.

I ordered three copies of the board together with all the parts for 18.30€ from Aisler in Germany, so I expect them to arrive in 7 or 8 days as they usually do. The parts are sometimes a bit more expensive when ordered through Aisler, but you don't have to come up with other stuff to get to 50€ free shipping at Digikey, so that's fine I guess...

Hope this design works :)